Liposuction is an invasive surgical procedure for altering the human form, specifically by removal of localized deposits of fatty tissues that are unresponsive to diet or exercise. The procedure is also known as suction lipectomy, lipolysis, and more recently as body contouring surgery, body sculpting surgery, or suction-assisted liposuction. It is most often performed by plastic surgeons, although dermatologists, gynecologists, and other surgical specialties also perform the procedure.
The liposuction procedure is typically accomplished by inserting a small liposuction cannula through an incision in the skin, applying a suction source to the end of the liposuction cannula that remains outside of the body, and forcing the working end of the liposuction cannula forward and backward in the layer of fatty tissue. The fatty tissue is torn, crushed, or avulsed, and is then aspirated through small openings along the sides of the liposuction cannula near the tip and then through a central lumen in the liposuction cannula to a tissue canister placed in-line with the liposuction cannula and the suction source. The procedure may involve multiple incisions and many passes of the liposuction cannula in each incision to achieve the desired cosmetic effect for the patient.
The liposuction procedure can be traumatic for the patient. The liposuction cannula does not discriminate between adipose tissue and other tissues such as nerves, blood vessels, or lymph tissues. The mechanical disruption of these tissues by the liposuction cannula may result in, among other things, bleeding, bruising, temporary numbness, pain, hyperpigmentation of the skin, or swelling. Complications may include infection, skin loss, or seroma formation. Patients generally have a post-operative course of healing that may range from about a week to several weeks or even a few months depending on the volume of adipose tissue removed. The final cosmetic result achieved for the patient is a function of the skill of the surgeon, the particular attributes of a patient, and the type of surgical instrumentation used in the surgery. A liposuction procedure may result in a less than uniform or smooth removal of adipose tissue, resulting in shape or skin contour irregularities and a final cosmetic result for the patient that is less than desirable.
Therefore, there has been a need to improve on the instrumentation and methods of liposuction for body contouring so that less damage would be done to the soft-tissues such as blood vessels, nerves, lymph tissue, and connective tissue while reducing the amount or number of adipose cells in a targeted area. Further, there has been a need to improve on the instrumentation and methods of liposuction for body contouring so that the there would be reduced risk of bleeding, bruising, pain, swelling, and other surgically related sequelae. Still further, there has been a need to improve on the instrumentation and methods of liposuction for body contouring so that adipose tissue could be sculpted in a more uniform and predictable manner so that an improved and more predictable cosmetic result could be achieved for the patient.
Recently, several instruments have combined ultrasonic vibrations and a liposuction cannula to improve upon the tissue discrimination capability of the liposuction cannula and to provide an instrument that removes adipose tissue more uniformly than prior liposuction cannulae. This technique is commonly referred to as ultrasound-assisted lipoplasty. Ultrasound-assisted lipoplasty is also an invasive surgical procedure, requiring an incision in the skin to insert the ultrasonically vibrating cannulae or probe. In a typical ultrasound-assisted lipoplasty procedure, an ultrasonically vibrating cannula or probe is inserted through an incision in the patient's skin and passed forward and backward through the adipose tissue layer, directly contacting the tissues to be treated. The ultrasonically vibrating cannula or probe fragments or emulsifies the adipose tissues, which are then usually aspirated either through a central lumen in the ultrasonically vibrating cannula or in a separate sequential step using an aspiration cannula. This approach is still an invasive surgical approach to body contouring surgery and therefore still suffers from similar post-surgical consequences and potential complications described above for the liposuction procedure.
The use of non-invasive (non-surgical) ultrasound for medical purposes has long been known, specifically for diagnostic imaging where the frequency and the ability to focus the ultrasonic beam determine the imaging resolution of the system. Diagnostic imaging systems typically operate at frequencies between 1 MHz and 30 MHz to achieve the desired imaging resolution, and operate at very low ultrasonic powers to minimize any potential damage to tissues. Diagnostic ultrasound is non-invasive, meaning that no incisions in the skin are required.
Focused ultrasound with sufficient ultrasonic power to fragment or otherwise destroy adipose tissue provides a non-invasive method of body contouring. An appropriately designed system focuses the ultrasonic energy at the depth of the targeted fatty tissue and has a significantly reduced energy density both above and below the focal zone, as well as lateral to the focal zone, thereby preserving the tissues above and below the focal zone. The benefits of a non-invasive body contouring method, compared to invasive (surgical) methods are: 1) a potentially shorter treatment time for the patient because a surgical operating room setup is not required; 2) increased safety because surgical trauma is eliminated and anesthesia is not required (general anesthesia, IV sedation, or injected local anesthetic); and 3) reduced recovery time and reduced post-operative pain. The primary limitations of a non-invasive focused ultrasound approach to body contouring, compared to invasive (surgical) methods, are: 1) less tissue can be treated in a single session, thereby requiring multiple treatments to achieve a desired body contour, and 2) results do not appear immediately, but rather over time as the body resorbs and processes destroyed adipose tissue.
Many patents disclose for the non-invasive use of ultrasound to heat soft-tissues of a patient, or to create cavitation within the soft-tissues of a patient, or to lyse or otherwise destroy fatty/adipose tissue. U.S. Pat. No. 5,143,063 to Fellner (1992) has a method for non-invasively eliminating excess healthy adipose tissue in the subcutaneous layer in humans, the method having steps of selecting a site on the body with excess fatty tissue to be eliminated; focusing radiant energy on the cells in the site to raise the temperature; and maintaining the radiant energy focused at the site until the adipose tissue at the site absorbs enough energy to cause cell destruction. U.S. Pat. No. 6,626,854 to Friedman (2003) has a system for destroying subcutaneous tissue with a transducer producing focused acoustic energy along a linear focal zone that is parallel to the plane of the tissue, drive circuitry, a controller for controlling the drive circuitry with a duty cycle of about 20% to minimize heating. U.S. Pat. No. 6,350,245 to Cimino (2002) has a hand-held ultrasonic device for fragmenting/emulsifying a volume of tissue below the skin with a focusing lens in the frequency range 100-250 kHz. U.S. Pat. No. 6,071,239 to Cribbs (2000) has a method of destroying fat cells in the subcutaneous layer with an ultrasonic transducer array with the beam focused in multiple discrete focal zones where the discrete focal zones are spaced sufficiently to preserve the structural integrity of the tissue. U.S. Pat. No. 6,443,914 to Constantino (2002) has a method of treating cellulite by application of ultrasound energy to cause damage to normal cells to reinforce a layer of connective tissue. U.S. Pat. No. 7,347,855 to Eshel (2008) has a method and apparatus for lysing adipose tissue using focused ultrasonic energy with a modulator that modulates the ultrasonic energy so most of the adipose tissue is lysed and the non-adipose tissue is not lysed. U.S. Pat. No. 6,607,498 to Eshel (2003) has a method and apparatus for lysing adipose tissue by applying an ultrasonic transducer to the skin of the patient and focusing the ultrasonic energy on the adipose tissue; electrically activating the ultrasonic transducer to transmit periodic waves sufficient to cause cavitation and lysis of the adipose tissue without damaging adjacent non-adipose tissue. U.S. Pat. No. 5,209,221 to Riedlinger (1993) has an ultrasonic system to treat pathological tissue by producing cavitation with a frequency greater than 20 kHz with a means to generate pulses, and a means to focus. U.S. Pat. No. 5,054,470 to Fry (1991) has an ultrasound treatment transducer with a focused beam, a flat PZT transducer plate, an acoustic coupling medium, a first pressurizing means and an air pressure means. U.S. Pat. No. 5,402,792 to Kimura (1995) has an ultrasonic apparatus with a wave emitting surface where the wave emitting surface has a plurality of different radii of curvature and different centers of concavity. U.S. Pat. No. 5,827,204 to Grandia (1998) has an apparatus for affecting tissue with low-frequency ultrasound and a means of superimposing a high frequency ultrasound signal to cause the amplitude to exceed the cavitation threshold. U.S. Pat. No. 4,315,514 to Drewes (1982) has a method of destroying selected cells by selecting a transmission path, determining a resonant frequency of the cells, comparing the transmissibility of the cells to the resonant frequency, selecting a destructive frequency, and transmitting energy at the destructive frequency. U.S. Pat. No. 5,507,790 to Weiss (1996) has a method of transdermally increasing the rate of lipolysis for body contour modification by focusing radiant energy (including ultrasonic energy with a focusing lens) on the target site to raise the temperature and cause the release of free fatty acids, thus reducing the volume of the fat cells.
These prior approaches have to varying degrees addressed issues relating to treatment efficacy and safety. But in many instances the approaches involve complex equipment and/or procedures that complicate the job of medical practitioners attempting to perform treatments. Moreover, damage to surrounding, non-targeted tissue remains a concern. There remains a need unmet by these prior approaches for non-invasive treatment methods and equipment that are safe and effective for treating targeted tissue while minimizing potential for damage to surrounding, non-targeted tissue, and that also are easy for individual medical practitioners to use to quickly perform a treatment.